1. It’s the user nginx runs under
2. Nginx is viewing it as the www-data user
3. Yes
4. Same permissions as any non-super user

When a folder is “user:group” you are referring to the fact that the folder is owned by user “user” who belongs to group “group”. When a folder is created (in this case, /var/www), the ownership goes to the user who created it. When the VPS was created, it was created by the root user so the folders . You can change the ownership to www-data:www-data or you can change permissions to allow NGINX (or any program operating at www-data:www-data) certain permissions (which is a whole other topic in itself).

If you wanted to change ownership of the folder to www-data and pretty much give NGINX full access, open up the console and issue the command “chown www-data:www-data /var/www” (if you are the root user). If you aren’t the root user, you’ll need to prefix the above command with “sudo”.

If you wanted to change the permissions, that’s a much more in depth command but generally speaking, you use the command “chmod”. Google it and there are plenty of articles that will go into the permissions more in depth.